[openwrt/openwrt] base-files: add gzip-compressed tar support to emmc_upgrade_tar()

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/21347caf7efb2a32c55c80612eae71cc4118bafc

commit 21347caf7efb2a32c55c80612eae71cc4118bafc
Author: INAGAKI Hiroshi <musashino.open at gmail.com>
AuthorDate: Sun Aug 4 18:14:43 2024 +0900

    base-files: add gzip-compressed tar support to emmc_upgrade_tar()
    
    Add support for the tar archive compressed by gzip to emmc_upgrade_tar()
    function.
    
    Signed-off-by: INAGAKI Hiroshi <musashino.open at gmail.com>
    Link: https://github.com/openwrt/openwrt/pull/16904
    Signed-off-by: Hauke Mehrtens <hauke at hauke-m.de>
---
 package/base-files/files/lib/upgrade/emmc.sh | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/package/base-files/files/lib/upgrade/emmc.sh b/package/base-files/files/lib/upgrade/emmc.sh
index 78e398d6d5..42450582b5 100644
--- a/package/base-files/files/lib/upgrade/emmc.sh
+++ b/package/base-files/files/lib/upgrade/emmc.sh
@@ -10,11 +10,15 @@ emmc_upgrade_tar() {
 	[ "$CI_DATAPART" -a -z "$EMMC_DATA_DEV" ] && export EMMC_DATA_DEV="$(find_mmc_part $CI_DATAPART $CI_ROOTDEV)"
 	local has_kernel
 	local has_rootfs
-	local board_dir=$(tar tf "$tar_file" | grep -m 1 '^sysupgrade-.*/$')
+	local gz
+	local board_dir
+	[ "$(identify_magic_long $(get_magic_long "$tar_file" cat))" = "gzip" ] && \
+		gz="z"
+	board_dir=$(tar t${gz}f "$tar_file" | grep -m 1 '^sysupgrade-.*/$')
 	board_dir=${board_dir%/}
 
-	tar tf "$tar_file" ${board_dir}/kernel 1>/dev/null 2>/dev/null && has_kernel=1
-	tar tf "$tar_file" ${board_dir}/root 1>/dev/null 2>/dev/null && has_rootfs=1
+	tar t${gz}f "$tar_file" ${board_dir}/kernel 1>/dev/null 2>/dev/null && has_kernel=1
+	tar t${gz}f "$tar_file" ${board_dir}/root 1>/dev/null 2>/dev/null && has_rootfs=1
 
 	[ "$has_rootfs" = 1 -a "$EMMC_ROOT_DEV" ] && {
 		# Invalidate kernel image while rootfs is being written
@@ -23,14 +27,14 @@ emmc_upgrade_tar() {
 			sync
 		}
 
-		export EMMC_ROOTFS_BLOCKS=$(($(tar xf "$tar_file" ${board_dir}/root -O | dd of="$EMMC_ROOT_DEV" bs=512 2>&1 | grep "records out" | cut -d' ' -f1)))
+		export EMMC_ROOTFS_BLOCKS=$(($(tar x${gz}f "$tar_file" ${board_dir}/root -O | dd of="$EMMC_ROOT_DEV" bs=512 2>&1 | grep "records out" | cut -d' ' -f1)))
 		# Account for 64KiB ROOTDEV_OVERLAY_ALIGN in libfstools
 		EMMC_ROOTFS_BLOCKS=$(((EMMC_ROOTFS_BLOCKS + 127) & ~127))
 		sync
 	}
 
 	[ "$has_kernel" = 1 -a "$EMMC_KERN_DEV" ] &&
-		export EMMC_KERNEL_BLOCKS=$(($(tar xf "$tar_file" ${board_dir}/kernel -O | dd of="$EMMC_KERN_DEV" bs=512 2>&1 | grep "records out" | cut -d' ' -f1)))
+		export EMMC_KERNEL_BLOCKS=$(($(tar x${gz}f "$tar_file" ${board_dir}/kernel -O | dd of="$EMMC_KERN_DEV" bs=512 2>&1 | grep "records out" | cut -d' ' -f1)))
 
 	if [ -z "$UPGRADE_BACKUP" ]; then
 		if [ "$EMMC_DATA_DEV" ]; then